Over the past decade, several techniques have been used for fusing together optical fibers. Fibers have been fused using an open flame, a heated nichrome wire, lasers, and by the most popular method of using an electric arc to weld fibers together.
Regardless of which technique is used, fibers which are to be joined together must be both held or clamped securely and aligned before a fusion joint is made. A variety of clamping devices are known which are intended to perform this function of holding an optical fiber without marring it. One such device is disclosed in U. S. Pat. No. 4,911,517 issued Mar. 27, 1990 in the name of Newell et al. entitled "Means for Clamping Fiber Optical Cable". The patent discloses a clamp in the form of a clip that is constrained to compress the fiber and grip it securely. The clamp appears to perform its intended function adequately, however it is preferable to have a clamp which is quick to use and which is inexpensive to manufacture.
After optical fibers have been spliced it is often necessary to test the splice by applying a predetermined tensile load to it. The break probability at prooftest, that is, the probability of a joint breaking while under test is greater as the magnitude of the tensile force applied to a spliced joint is increased. The greater the tensile force a splice can withstand, the greater the probability the joint will last without breaking.
A variety of manufacturers have produced prooftesters; for example, Sumitumo Electric Industries of Japan manufactures a Type-35 optical fiber fusion splicer including a prooftester which tests fusion splices with a tensile load of between 50 and 500 grams. This prooftester includes clamps for securely holding two portions of a spliced fiber and a stepper motor which applies tension to the splice by stepwise increasing the distance between the clamps. The force applied by the stepper motor may be adjusted to adjust the tension applied to the splice. Prooftesters which include stepper motors as described tend to be costly, bulky, and somewhat fragile.